<div id="app">
  <h1>{{ title }}</h1>
  <p>观察渲染函数</p>
  <pre style="border: 1px solid black;
  background-color: #ffffda;">{{renderFunc}}</pre>
</div>
<script src="https://unpkg.com/vue@next"></script>
<script>
  const { createApp } = Vue
  const app = createApp({
    data() {
      return {
        title: '说说从template到render的处理过程',
        renderFunc: ''
      }
    },
  }).mount('#app')
  app.renderFunc = app.$options.render
</script>